Browsing by Subject "organic chemistry"
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Item Evaluation and Development of Weakly Coordinating Cations and Their Application to Charge-Enhanced Base Organocatalysis(2023-02) Dempsey, StephenReactive ions are ubiquitous species in diverse areas of chemistry. Numerous studies have shown that cations paired with weakly coordinating anions can lead to potent and unexpected reactivity. In contrast, relatively little has been done with weakly coordinating cations paired with reactive anions. In the first part of this dissertation, current literature-standard weakly coordinating cations are examined and the synthesis and evaluation of new phosphonium cations is presented. Organocatalysis is a powerful component of the modern synthetic chemist’s toolbox. Previous work in the Kass group has shown that the inclusion of a positive charge onto acidic organocatalyst motifs leads to potent reactivity enhancements. The latter half of this dissertation discusses the inverse, where an anionic center was included on a basic pyridine moiety and the resulting electrostatically enhanced base organocatalysts reactivity was examined. Additionally, an exploration of the ionic structure of the most potent catalysts via a variety of methods is presented.Item Supporting data for Polymeric medical sutures: An exploration of polymers and green chemistry(2018-01-17) Knutson, Cassandra M; Schneiderman, Deborah K; Yu, Ming; Javner, Cassidy H; Distefano, Mark D; Wissinger, Jane E; jwiss@umn.edu; Wissinger, Jane EThese files contain data along with associated output from instrumentation supporting all results reported in Knutson, C. M.; Schneiderman, D. K.; Yu, M.; Javner, C. H.; Distefano, M. D.; Wissinger, J. E. Polymeric medical sutures: An exploration of polymers and green chemistry. J. Chem. Educ. 2017, 94, 1761–1765. In Knutson, et. al. it was found that with new K–12 national science standards emerging, there is an increased need for experiments that integrate engineering into the context of society. Here we describe a chemistry experiment that combines science and engineering principles while introducing basic polymer and green chemistry concepts. Using medical sutures as a platform for investigating polymers, students explore the physical and mechanical properties of threads drawn from poly(ε-caprolactone) samples of different molecular masses and actual purchased absorbable and nonabsorbable medical sutures. An inquiry-based part of the experiment tasks students with designing their own experiment to probe the potential of melt blending poly(ε-caprolactone) with commercially available polylactide products in order to modify the properties of the “sutures” drawn. Through these lessons students gain an appreciation for the importance of plastics in our society and how scientists are working to develop more sustainable alternatives. Overall, this laboratory experiment provides a feasible, versatile, sophisticated laboratory experience that engages students in a relatable topic and meets many of the Next Generation Science Standards.